WASHINGTON – Two weeks of antibiotic therapy with rifaximin provided relief from functional dyspepsia symptoms in a phase III double-blind, randomized trial.
“This is the first study that demonstrates that rifaximin is efficacious in the treatment of functional dyspepsia, particularly for global dyspeptic symptoms, bloating, and possibly belching. Our finding may suggest a role for the gut microbiota in the pathogenesis of functional dyspepsia,” Dr. Victoria Tan said at the annual Digestive Disease Week.
Rifaximin (Xifaxan) works by reducing or altering bacteria in the gut and has been shown to be efficacious in the treatment of diarrhea-predominant irritable bowel syndrome. It is approved to treat traveler’s diarrhea caused by Escherichia coli and to prevent hepatic encephalopathy.
The study randomly assigned 95 consecutive adults with functional dyspepsia as per ROME III criteria who had a normal gastroscopy within the last 2 years, had active symptoms in the month prior to enrollment, and were Helicobacter pylori negative, to rifaximin 400 mg or placebo three times a day for 2 weeks. In all, 33 rifaximin and 39 placebo patients were evaluable for the primary efficacy outcome of adequate relief of global dyspeptic symptoms (either no or mild dyspeptic symptoms) at any of the follow-up time points.
At baseline, 77% of patients had moderate to severe global dyspepsia symptoms, 74% of the placebo group and 55%% of the rifaximin group had moderate to severe belching, and roughly half of all patients were not on any GI medications. Mean age of the patients was 52 years.
Global dyspepsia symptoms improved with rifaximin beginning at week 2 and significantly favored rifaximin by week 8, with 23.5% of rifaximin patients reporting moderate to severe symptoms compared with 47.4% given placebo (P value = .04), said Dr. Tan of the University of Hong Kong.
Rates of moderate to severe belching were significantly improved with rifaximin at week 4 compared with placebo (14.3% vs. 35.7%; P = .03), but this difference was no longer significant at week 8 (26.5% vs. 29%).
The story was similar for moderate to severe bloating: Rates declined significantly with rifaximin at week 4 (20% vs. 43%; P = .03), but were no longer significant at week 8 (26.5% vs. 34.2%), she said.
A subgroup analysis of female patients showed significant improvements in moderate to severe global dyspeptic symptoms with rifaximin compared with placebo at week 4 (20.8% vs. 59.4%; P = .006) and week 8 (20% vs. 48.4%; P = .048).
Treatment response was not reflected in change in hydrogen breath response, Dr. Tan said. Results of a 3-hour hydrogen breath test performed after a 12-hour overnight fast showed no differences between the rifaximin and placebo groups for H2 peak above baseline (2.94 ppm vs. 0.11 ppm; P = .29), H2 area under the curve (+43.64 ppm vs. –49.71 ppm; P = .76), and oro-cecal transit time (24.23 minutes vs. 16.5 minutes; P = .68).
Adverse events were very similar between the two groups at both 4 and 8 weeks, Dr. Tan said. Only one major event occurred, a severe case of acute hepatitis in a woman in the placebo arm who also took traditional Chinese herbs.
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